This idea relates to a copy paper exhausting roller unit used in an electrophotographic copying machine.
A schematic view of an ordinary copying machine is shown in FIG. 1 in which a toner image developed on a photoconductive drum "a" is transferred on a copy paper, which is transported by a gripper bar "c" in the direction shown by an arrow A into a thermal fuser "d" in which the image is thermally fixed by means of a heater "e". Then the copy paper is fed into a roller unit "h" through a pair of guide plates "f" and "g". The roller unit exhausts the paper sheet outside the machine in such manner that the sheet falls on receiving tray "i" keeping its front side up (without turning over). In order to avoid turning over of the sheet during the descent to the tray the sheet should be imparted with rigidity along its longitudinal direction, which is ordinarily accomplished by giving it a crease parallel to the moving direction of the sheet by passing the sheet between the roller unit. However, in electrophotographic copier employing either dry or wet development it is not preferred to bring the surface of the copy paper carrying toner image into contact with the surface of a roller since such contact deteriorates the image quality. Thus, it is not desirable to use in such casting roller unit a pair of rollers which contact the engage with each other the entire lengths thereof.
One may resort to another conveying method in which the copy paper, after receiving toner image and passing through the thermal fixer, is delivered by a conveyer belt to the tray. In this method, however, accidental brief interruption of electric power supply during the passage of the copy sheet through the fixer, will cause a fire accident; the sheet begins to burn by the stored heat in the fixer, then with the input of the power supply, the burning sheet is delivered outside the copier to cause a fire to spread in the room in which the copier is placed.
This idea has been made in consideration of this background and its principal object is to disclose a new copy paper exhausting roller unit which imparts the copy sheet suitable rigidity along its moving direction by giving creases without coming into contact with the entire surface of the sheet and which can also extinguish the fire of a burning sheet before delivering outside the machine.